The invention relates to a device for loading containers that are open or can be vented, containers for fine particulate materials, said device being part of a pneumatic conveyance system, in particular such a system using dense layer transportation. The invention relates also to the use of the said device.
Pneumatic transportation systems for moving fine particulate material feed the said material from a main supply line to a plurality of containers, usually in the form of silos. A branch supply line runs from the main supply line to each feeding port in the containers, regardless of whether each silo features one or more such inlets. However, in known conveyance systems, apart from these branch supply lines other facilities must be provided in order that the filling process stops at a given point in time and the container in question closed:
For each loading point two valves are necessary, one in the main supply line and one in the branch supply line.
For each loading point or each container a level switch is necessary when there is a plurality of loading points in each container.
On loading the containers all loading points are charged in succession in that the main supply line is closed off immediately behind the branch supply line in question and the latter opened for feeding. This process is controlled by an electronic switching circuit which receives regulatory impulses from the level switches.
Problems have often been encountered with mechanically actuated shut-off valves as the granular-to-dusty material being charged can penetrate the bearings and impair their function. In U.S. Pat. Nos. 4,615,648 and 4,450,053 a marked improvement is proposed in that branch supply lines can be connected up to dense layer feeding systems without requiring mechanical devices in the supply line. Using magnetic valves a plug of material can be formed in the branch connection and namely such which do not extend to the ball valve in the supply line. On the one hand this enables supply systems to be constructed that do not require branches or three-way valves, and on the other hand the ball valves that close off the supply lines are protected from direct contact with the particulate material. When the ball valve is open, contact with the particulate material is less dangerous for that ball valve. In the case of branch supply lines for loading containers the magnetic valves that shut off the compressed air supply to the dense layer conveyance system are regulated via level switches.
The object of the present invention is to develop a device for a pneuamtic system for conveying fine particulate material to a plurality of loading points for charging containers that can be vented, in particular dense layer transportation systems, the said device being simple, energy-saving and designed to load the said containers and close the inlet charging port/ports of the container without individual level switches or other individual regulating systems being necessary, and such that the said device can be employed for a wide range of applications.